package dedup

import (
	"context"
	"fmt"
	"runtime"
	"sync"
	"sync/atomic"
	"time"
)

// MemoryOptimizer handles memory usage optimization for deduplication
type MemoryOptimizer interface {
	// OptimizeMemoryUsage optimizes memory usage for deduplication
	OptimizeMemoryUsage(ctx context.Context, config *MemoryConfig) error

	// MonitorMemoryUsage monitors and reports memory usage
	MonitorMemoryUsage(ctx context.Context) (*MemoryMetrics, error)

	// ManageMemoryPool manages memory pool for efficient allocation
	ManageMemoryPool(ctx context.Context, size int64) error

	// GetMemoryStats returns memory usage statistics
	GetMemoryStats() MemoryStats
}

// MemoryConfig contains memory optimization configuration
type MemoryConfig struct {
	MaxMemoryUsage      int64
	TargetMemoryUsage   int64
	PoolSize           int64
	EnablePooling      bool
	EnableCompression  bool
	EnableStreaming    bool
	MaxChunkSize       int64
	MaxConcurrentOps   int
	GCThreshold        float64
	EvictionPolicy     string
}

// MemoryMetrics contains memory usage metrics
type MemoryMetrics struct {
	CurrentUsage      int64
	PeakUsage         int64
	PoolUsage         int64
	CacheUsage        int64
	BufferUsage       int64
	MetadataUsage     int64
	GCCount           int64
	GCTime            time.Duration
	AllocationRate    float64
	Fragmentation     float64
	Timestamp         time.Time
}

// MemoryStats contains memory usage statistics
type MemoryStats struct {
	TotalAllocations   int64
	TotalDeallocations int64
	PoolHitRate        float64
	CompressionRatio   float64
	StreamingSavings   int64
	EvictionCount      int64
	AverageUsage       float64
	PeakUsage          int64
	OptimizationCount  int64
}

// SmartMemoryOptimizer implements intelligent memory optimization
type SmartMemoryOptimizer struct {
	mu                sync.RWMutex
	config            MemoryConfig
	stats             MemoryStats
	memoryPool        *MemoryPool
	cacheManager      *MemoryCacheManager
	bufferManager     *BufferManager
	compressionEngine *CompressionEngine
	gcManager         *GCManager
	usageMonitor      *UsageMonitor
	optimizationRules map[string]MemoryOptimizationRule
	optimizer         *SmartMemoryOptimizer // Reference to parent for rules
}

// MemoryPool manages memory pooling for efficient allocation
type MemoryPool struct {
	mu           sync.RWMutex
	pools        map[string]*Pool
	stats        PoolStats
	maxSize      int64
	currentSize  int64
	evictionPolicy string
}

// Pool represents a memory pool for specific object sizes
type Pool struct {
	size        int
	objects     chan []byte
	inUse       int64
	allocations int64
	deallocations int64
}

// PoolStats contains pool statistics
type PoolStats struct {
	HitRate      float64
	MissRate     float64
	EvictionCount int64
	TotalAllocations int64
	TotalDeallocations int64
	AverageLatency time.Duration
}

// MemoryCacheManager manages memory-based caching
type MemoryCacheManager struct {
	mu              sync.RWMutex
	cache           map[string]*MemoryCacheEntry
	maxSize         int64
	currentSize     int64
	evictionPolicy  string
	stats           MemoryCacheStats
}

// MemoryCacheEntry represents a memory cache entry
type MemoryCacheEntry struct {
	Key        string
	Data       []byte
	Size       int64
	AccessTime time.Time
	AccessCount int64
	Compressed bool
	CompressedSize int64
}

// MemoryCacheStats contains memory cache statistics
type MemoryCacheStats struct {
	HitRate        float64
	MissRate       float64
	CompressionRatio float64
	EvictionCount  int64
	EntryCount     int64
	TotalSize      int64
	CompressedSize int64
}

// BufferManager manages buffer allocation and reuse
type BufferManager struct {
	mu           sync.RWMutex
	buffers      map[int]*BufferPool
	maxBufferSize int
	stats        BufferStats
}

// BufferPool manages buffers of specific size
type BufferPool struct {
	size        int
	buffers     chan []byte
	allocations int64
	deallocations int64
	inUse       int64
}

// BufferStats contains buffer statistics
type BufferStats struct {
	HitRate      float64
	MissRate     float64
	ReuseCount   int64
	AllocationCount int64
	AverageLatency time.Duration
}

// CompressionEngine handles memory-efficient compression
type CompressionEngine struct {
	mu              sync.RWMutex
	algorithms      map[string]CompressionAlgorithm
	defaultAlgorithm string
	compressionThreshold int64
	stats           CompressionStats
}

// CompressionAlgorithm represents a compression algorithm
type CompressionAlgorithm interface {
	Compress(data []byte) ([]byte, error)
	Decompress(data []byte) ([]byte, error)
	GetName() string
	GetRatio() float64
}

// CompressionStats contains compression statistics
type CompressionStats struct {
	TotalCompressed   int64
	TotalDecompressed int64
	CompressionRatio  float64
	AverageTime       time.Duration
	AlgorithmUsage    map[string]int64
}

// GCManager manages garbage collection optimization
type GCManager struct {
	mu              sync.RWMutex
	gcCount         int64
	gcTime          time.Duration
	lastGC          time.Time
	gcThreshold     float64
	forcedGCs       int64
	stats           GCStatistics
}

// GCStats contains garbage collection statistics
type GCStatistics struct {
	TotalGCs        int64
	ForcedGCs       int64
	AverageGCTime   time.Duration
	GCFrequency     float64
	MemoryRecovered int64
}

// UsageMonitor monitors memory usage patterns
type UsageMonitor struct {
	mu              sync.RWMutex
	usageHistory    []UsageSnapshot
	maxHistorySize  int
	currentUsage    int64
	peakUsage       int64
	averageUsage    float64
	growthRate      float64
	predictionModel *UsagePredictionModel
}

// UsageSnapshot represents a memory usage snapshot
type UsageSnapshot struct {
	Timestamp    time.Time
	Usage        int64
	AllocationRate float64
	GCActivity   bool
}

// UsagePredictionModel predicts future memory usage
type UsagePredictionModel struct {
	mu              sync.RWMutex
	historicalData  []UsageSnapshot
	modelType       string
	accuracy        float64
	predictions     []UsagePrediction
}

// UsagePrediction represents a usage prediction
type UsagePrediction struct {
	Timestamp time.Time
	PredictedUsage int64
	Confidence     float64
}

// MemoryOptimizationRule represents a memory optimization rule
type MemoryOptimizationRule struct {
	Condition func(*MemoryMetrics) bool
	Action    func(context.Context, *SmartMemoryOptimizer) error
}

// NewSmartMemoryOptimizer creates a new smart memory optimizer
func NewSmartMemoryOptimizer(config MemoryConfig) (*SmartMemoryOptimizer, error) {
	if config.MaxMemoryUsage <= 0 {
		config.MaxMemoryUsage = 1024 * 1024 * 1024 // 1GB default
	}

	if config.TargetMemoryUsage <= 0 {
		config.TargetMemoryUsage = config.MaxMemoryUsage / 2
	}

	optimizer := &SmartMemoryOptimizer{
		config:            config,
		stats:             MemoryStats{},
		optimizationRules: initializeMemoryOptimizationRules(),
	}

	// Initialize memory pool
	optimizer.memoryPool = NewMemoryPool(config.PoolSize, config.EvictionPolicy)

	// Initialize cache manager
	optimizer.cacheManager = NewMemoryCacheManager(config.MaxMemoryUsage/4, config.EvictionPolicy)

	// Initialize buffer manager
	optimizer.bufferManager = NewBufferManager(1024 * 1024) // 1MB max buffer size

	// Initialize compression engine
	optimizer.compressionEngine = NewCompressionEngine()

	// Initialize GC manager
	optimizer.gcManager = NewGCManager(config.GCThreshold)

	// Initialize usage monitor
	optimizer.usageMonitor = NewUsageMonitor(1000) // 1000 snapshots max

	return optimizer, nil
}

// OptimizeMemoryUsage optimizes memory usage for deduplication
func (o *SmartMemoryOptimizer) OptimizeMemoryUsage(ctx context.Context, config *MemoryConfig) error {
	o.mu.Lock()
	defer o.mu.Unlock()

	startTime := time.Now()

	// Monitor current usage (internal version without locks)
	currentMetrics, err := o.monitorMemoryUsageInternal(ctx)
	if err != nil {
		return fmt.Errorf("failed to monitor memory usage: %w", err)
	}

	// Apply optimization rules
	if err := o.applyMemoryOptimizationRules(ctx, currentMetrics); err != nil {
		return fmt.Errorf("failed to apply optimization rules: %w", err)

	}

	// Optimize memory pool
	if err := o.optimizeMemoryPool(ctx, currentMetrics); err != nil {
		return fmt.Errorf("failed to optimize memory pool: %w", err)
	}

	// Optimize cache
	if err := o.optimizeCache(ctx, currentMetrics); err != nil {
		return fmt.Errorf("failed to optimize cache: %w", err)
	}

	// Optimize buffers
	if err := o.optimizeBuffers(ctx, currentMetrics); err != nil {
		return fmt.Errorf("failed to optimize buffers: %w", err)
	}

	// Force GC if needed
	if err := o.optimizeGC(ctx, currentMetrics); err != nil {
		return fmt.Errorf("failed to optimize GC: %w", err)
	}

	// Update statistics
	o.stats.OptimizationCount++
	o.stats.AverageUsage = float64(currentMetrics.CurrentUsage)
	if currentMetrics.CurrentUsage > o.stats.PeakUsage {
		o.stats.PeakUsage = currentMetrics.CurrentUsage
	}

	optimizationTime := time.Since(startTime)
	if optimizationTime > 0 {
		// Update usage monitor
		o.usageMonitor.AddSnapshot(UsageSnapshot{
			Timestamp:    time.Now(),
			Usage:        currentMetrics.CurrentUsage,
			AllocationRate: currentMetrics.AllocationRate,
			GCActivity:   currentMetrics.GCCount > 0,
		})
	}

	return nil
}

// MonitorMemoryUsage monitors and reports memory usage
func (o *SmartMemoryOptimizer) MonitorMemoryUsage(ctx context.Context) (*MemoryMetrics, error) {
	o.mu.RLock()
	defer o.mu.RUnlock()

	// Get runtime memory stats
	var m runtime.MemStats
	runtime.ReadMemStats(&m)

	// Calculate metrics
	metrics := &MemoryMetrics{
		CurrentUsage:   int64(m.Alloc),
		PeakUsage:      o.usageMonitor.GetPeakUsage(),
		PoolUsage:      o.memoryPool.GetCurrentSize(),
		CacheUsage:     o.cacheManager.GetCurrentSize(),
		BufferUsage:    o.bufferManager.GetCurrentSize(),
		MetadataUsage:  int64(m.Sys - m.Alloc),
		GCCount:        int64(m.NumGC),
		GCTime:         time.Duration(m.PauseTotalNs),
		AllocationRate: float64(m.TotalAlloc) / float64(time.Since(time.Unix(int64(m.LastGC/1e9), 0)).Seconds()),
		Fragmentation:  float64(m.Sys-m.Alloc) / float64(m.Sys),
		Timestamp:      time.Now(),
	}

	return metrics, nil
}

// monitorMemoryUsageInternal is an internal version that doesn't require locks
func (o *SmartMemoryOptimizer) monitorMemoryUsageInternal(ctx context.Context) (*MemoryMetrics, error) {
	// Get runtime memory stats
	var m runtime.MemStats
	runtime.ReadMemStats(&m)

	// Calculate metrics
	metrics := &MemoryMetrics{
		CurrentUsage:   int64(m.Alloc),
		PeakUsage:      o.usageMonitor.GetPeakUsage(),
		PoolUsage:      o.memoryPool.GetCurrentSize(),
		CacheUsage:     o.cacheManager.GetCurrentSize(),
		BufferUsage:    o.bufferManager.GetCurrentSize(),
		MetadataUsage:  int64(m.Sys - m.Alloc),
		GCCount:        int64(m.NumGC),
		GCTime:         time.Duration(m.PauseTotalNs),
		AllocationRate: float64(m.TotalAlloc) / float64(time.Since(time.Unix(int64(m.LastGC/1e9), 0)).Seconds()),
		Fragmentation:  float64(m.Sys-m.Alloc) / float64(m.Sys),
		Timestamp:      time.Now(),
	}

	return metrics, nil
}

// ManageMemoryPool manages memory pool for efficient allocation
func (o *SmartMemoryOptimizer) ManageMemoryPool(ctx context.Context, size int64) error {
	o.mu.Lock()
	defer o.mu.Unlock()

	return o.memoryPool.Resize(size)
}

// GetMemoryStats returns memory usage statistics
func (o *SmartMemoryOptimizer) GetMemoryStats() MemoryStats {
	o.mu.RLock()
	defer o.mu.RUnlock()

	return o.stats
}

// applyMemoryOptimizationRules applies intelligent memory optimization rules
func (o *SmartMemoryOptimizer) applyMemoryOptimizationRules(ctx context.Context, metrics *MemoryMetrics) error {
	for ruleName, rule := range o.optimizationRules {
		if rule.Condition(metrics) {
			if err := rule.Action(ctx, o); err != nil {
				return fmt.Errorf("failed to apply rule %s: %w", ruleName, err)
			}
		}
	}
	return nil
}

// optimizeMemoryPool optimizes memory pool usage
func (o *SmartMemoryOptimizer) optimizeMemoryPool(ctx context.Context, metrics *MemoryMetrics) error {
	// Adjust pool size based on usage patterns
	if metrics.PoolUsage < int64(float64(o.memoryPool.maxSize)*0.3) {
		// Pool is underutilized, reduce size
		o.memoryPool.Resize(int64(float64(o.memoryPool.maxSize) * 0.8))
	} else if metrics.PoolUsage > int64(float64(o.memoryPool.maxSize)*0.9) {
		// Pool is overutilized, increase size if possible
		if metrics.CurrentUsage < int64(float64(o.config.MaxMemoryUsage)*0.8) {
			o.memoryPool.Resize(int64(float64(o.memoryPool.maxSize) * 1.2))
		}
	}

	// Clean up unused pools
	o.memoryPool.CleanupUnusedPools()

	return nil
}

// optimizeCache optimizes cache usage
func (o *SmartMemoryOptimizer) optimizeCache(ctx context.Context, metrics *MemoryMetrics) error {
	// Adjust cache size based on hit rate and memory pressure
	cacheStats := o.cacheManager.GetStats()

	if cacheStats.HitRate < 0.3 && metrics.CacheUsage < int64(float64(o.cacheManager.maxSize)*0.7) {
		// Low hit rate with available space, increase cache size
		o.cacheManager.Resize(int64(float64(o.cacheManager.maxSize) * 1.1))
	} else if cacheStats.HitRate > 0.8 && metrics.CacheUsage > int64(float64(o.cacheManager.maxSize)*0.9) {
		// High hit rate with high usage, maintain current size
		// but optimize compression
		o.cacheManager.EnableCompression()
	}

	// Evict stale entries
	o.cacheManager.EvictStaleEntries()

	return nil
}

// optimizeBuffers optimizes buffer usage
func (o *SmartMemoryOptimizer) optimizeBuffers(ctx context.Context, metrics *MemoryMetrics) error {
	// Adjust buffer pool sizes based on usage
	bufferStats := o.bufferManager.GetStats()

	if bufferStats.HitRate < 0.5 {
		// Low hit rate, resize buffer pools
		o.bufferManager.OptimizePoolSizes()
	}

	// Clean up unused buffers
	o.bufferManager.CleanupUnusedBuffers()

	return nil
}

// optimizeGC optimizes garbage collection
func (o *SmartMemoryOptimizer) optimizeGC(ctx context.Context, metrics *MemoryMetrics) error {
	// Check if GC is needed
	if metrics.Fragmentation > 0.3 || metrics.CurrentUsage > int64(float64(o.config.MaxMemoryUsage)*0.9) {
		// Force GC
		runtime.GC()
		o.gcManager.RecordGC()
	}

	// Update GC threshold if needed
	if metrics.GCCount > 10 && metrics.GCTime > time.Second {
		// Too much time spent in GC, adjust threshold
		o.gcManager.AdjustThreshold(-0.1)
	}

	return nil
}

// NewMemoryPool creates a new memory pool
func NewMemoryPool(maxSize int64, evictionPolicy string) *MemoryPool {
	return &MemoryPool{
		pools:          make(map[string]*Pool),
		maxSize:        maxSize,
		evictionPolicy: evictionPolicy,
	}
}

// GetPool gets or creates a pool for the given size
func (mp *MemoryPool) GetPool(size int) *Pool {
	mp.mu.Lock()
	defer mp.mu.Unlock()

	poolKey := getPoolKey(size)
	if pool, exists := mp.pools[poolKey]; exists {
		return pool
	}

	// Create new pool
	pool := &Pool{
		size:    size,
		objects: make(chan []byte, 100), // Buffer up to 100 objects
	}
	mp.pools[poolKey] = pool
	return pool
}

// Get gets an object from the pool
func (mp *MemoryPool) Get(size int) ([]byte, error) {
	pool := mp.GetPool(size)
	if pool == nil {
		return make([]byte, size), nil
	}

	select {
	case obj := <-pool.objects:
		atomic.AddInt64(&pool.inUse, 1)
		return obj, nil
	default:
		// Pool is empty, allocate new object
		return make([]byte, pool.size), nil
	}
}

// Put returns an object to the pool
func (mp *MemoryPool) Put(obj []byte) error {
	pool := mp.GetPool(len(obj))
	if pool == nil {
		return nil
	}

	select {
	case pool.objects <- obj:
		atomic.AddInt64(&pool.inUse, -1)
		return nil
	default:
		// Pool is full, let GC handle it
		return nil
	}
}

// Resize resizes the memory pool
func (mp *MemoryPool) Resize(newSize int64) error {
	mp.mu.Lock()
	defer mp.mu.Unlock()

	mp.maxSize = newSize
	return nil
}

// GetCurrentSize returns current pool size
func (mp *MemoryPool) GetCurrentSize() int64 {
	mp.mu.RLock()
	defer mp.mu.RUnlock()

	size := int64(0)
	for _, pool := range mp.pools {
		size += int64(pool.size) * int64(len(pool.objects))
	}
	return size
}

// CleanupUnusedPools cleans up unused pools
func (mp *MemoryPool) CleanupUnusedPools() {
	mp.mu.Lock()
	defer mp.mu.Unlock()

	// Remove pools with low usage
	for key, pool := range mp.pools {
		if atomic.LoadInt64(&pool.inUse) == 0 && len(pool.objects) > 10 {
			delete(mp.pools, key)
		}
	}
}

// NewMemoryCacheManager creates a new memory cache manager
func NewMemoryCacheManager(maxSize int64, evictionPolicy string) *MemoryCacheManager {
	return &MemoryCacheManager{
		cache:          make(map[string]*MemoryCacheEntry),
		maxSize:        maxSize,
		evictionPolicy: evictionPolicy,
	}
}

// Get gets data from cache
func (mcm *MemoryCacheManager) Get(key string) ([]byte, bool) {
	mcm.mu.RLock()
	defer mcm.mu.RUnlock()

	if entry, exists := mcm.cache[key]; exists {
		entry.AccessTime = time.Now()
		entry.AccessCount++

		data := entry.Data
		if entry.Compressed {
			// Decompress data
			// This is a simplified implementation
			data = entry.Data
		}

		return data, true
	}

	return nil, false
}

// Set stores data in cache
func (mcm *MemoryCacheManager) Set(key string, data []byte) error {
	mcm.mu.Lock()
	defer mcm.mu.Unlock()

	dataSize := int64(len(data))

	// Check if we need to evict entries
	if mcm.currentSize+dataSize > mcm.maxSize {
		mcm.evictEntries(dataSize)
	}

	// Try to compress data
	compressed := false
	compressedData := data
	if len(data) > 1024 { // Only compress data larger than 1KB
		// This is a simplified compression check
		// In reality, you would use actual compression
		compressed = true
	}

	entry := &MemoryCacheEntry{
		Key:        key,
		Data:       compressedData,
		Size:       dataSize,
		AccessTime: time.Now(),
		AccessCount: 1,
		Compressed: compressed,
		CompressedSize: int64(len(compressedData)),
	}

	mcm.cache[key] = entry
	mcm.currentSize += dataSize
	mcm.stats.EntryCount++
	mcm.stats.TotalSize += dataSize
	if compressed {
		mcm.stats.CompressedSize += int64(len(compressedData))
	}

	return nil
}

// GetStats returns cache statistics
func (mcm *MemoryCacheManager) GetStats() MemoryCacheStats {
	mcm.mu.RLock()
	defer mcm.mu.RUnlock()

	return mcm.stats
}

// Resize resizes the cache
func (mcm *MemoryCacheManager) Resize(newSize int64) {
	mcm.mu.Lock()
	defer mcm.mu.Unlock()

	mcm.maxSize = newSize
	if mcm.currentSize > mcm.maxSize {
		mcm.evictEntries(mcm.currentSize - mcm.maxSize)
	}
}

// EnableCompression enables compression for cache entries
func (mcm *MemoryCacheManager) EnableCompression() {
	mcm.mu.Lock()
	defer mcm.mu.Unlock()

	// Enable compression for new entries
	// This is a simplified implementation
}

// EvictStaleEntries evicts stale cache entries
func (mcm *MemoryCacheManager) EvictStaleEntries() {
	mcm.mu.Lock()
	defer mcm.mu.Unlock()

	// Remove entries that haven't been accessed in the last hour
	cutoffTime := time.Now().Add(-1 * time.Hour)
	for key, entry := range mcm.cache {
		if entry.AccessTime.Before(cutoffTime) {
			mcm.currentSize -= entry.Size
			delete(mcm.cache, key)
			mcm.stats.EntryCount--
			mcm.stats.TotalSize -= entry.Size
			mcm.stats.EvictionCount++
		}
	}
}

// GetCurrentSize returns current cache size
func (mcm *MemoryCacheManager) GetCurrentSize() int64 {
	mcm.mu.RLock()
	defer mcm.mu.RUnlock()

	return mcm.currentSize
}

// evictEntries evicts entries based on the eviction policy
func (mcm *MemoryCacheManager) evictEntries(targetSize int64) {
	// Simple LRU eviction
	var oldestKey string
	var oldestTime time.Time

	for key, entry := range mcm.cache {
		if oldestKey == "" || entry.AccessTime.Before(oldestTime) {
			oldestKey = key
			oldestTime = entry.AccessTime
		}
	}

	if oldestKey != "" {
		if entry, exists := mcm.cache[oldestKey]; exists {
			mcm.currentSize -= entry.Size
			delete(mcm.cache, oldestKey)
			mcm.stats.EntryCount--
			mcm.stats.TotalSize -= entry.Size
			mcm.stats.EvictionCount++
		}
	}
}

// Helper functions

func getPoolKey(size int) string {
	// Round size to nearest power of 2
	power := 1
	for power < size {
		power *= 2
	}
	return fmt.Sprintf("pool_%d", power)
}

func initializeMemoryOptimizationRules() map[string]MemoryOptimizationRule {
	rules := make(map[string]MemoryOptimizationRule)

	// High memory usage rule
	rules["high_memory"] = MemoryOptimizationRule{
		Condition: func(metrics *MemoryMetrics) bool {
			return metrics.CurrentUsage > 1024*1024*1024 // 1GB
		},
		Action: func(ctx context.Context, optimizer *SmartMemoryOptimizer) error {
			// Force cache eviction and buffer cleanup
			optimizer.cacheManager.EvictStaleEntries()
			optimizer.bufferManager.CleanupUnusedBuffers()
			// Force GC
			runtime.GC()
			return nil
		},
	}

	// High fragmentation rule
	rules["high_fragmentation"] = MemoryOptimizationRule{
		Condition: func(metrics *MemoryMetrics) bool {
			return metrics.Fragmentation > 0.3
		},
		Action: func(ctx context.Context, optimizer *SmartMemoryOptimizer) error {
			// Force GC to reduce fragmentation
			runtime.GC()
			optimizer.gcManager.RecordGC()
			return nil
		},
	}

	// Low pool hit rate rule
	rules["low_pool_hit_rate"] = MemoryOptimizationRule{
		Condition: func(metrics *MemoryMetrics) bool {
			return metrics.PoolUsage > 0 && metrics.PoolUsage < 1024*1024 // 1MB threshold
		},
		Action: func(ctx context.Context, optimizer *SmartMemoryOptimizer) error {
			// Resize pools and clean up unused ones
			optimizer.memoryPool.CleanupUnusedPools()
			return nil
		},
	}

	return rules
}

// Placeholder implementations for other components

func NewBufferManager(maxBufferSize int) *BufferManager {
	return &BufferManager{
		buffers:       make(map[int]*BufferPool),
		maxBufferSize: maxBufferSize,
	}
}

func (bm *BufferManager) GetCurrentSize() int64 {
	bm.mu.RLock()
	defer bm.mu.RUnlock()

	size := int64(0)
	for _, pool := range bm.buffers {
		size += int64(pool.size) * int64(len(pool.buffers))
	}
	return size
}

func (bm *BufferManager) GetStats() BufferStats {
	bm.mu.RLock()
	defer bm.mu.RUnlock()

	return bm.stats
}

func (bm *BufferManager) OptimizePoolSizes() {
	// Implementation would optimize buffer pool sizes based on usage patterns
}

func (bm *BufferManager) CleanupUnusedBuffers() {
	// Implementation would clean up unused buffers
}

func NewCompressionEngine() *CompressionEngine {
	return &CompressionEngine{
		algorithms:       make(map[string]CompressionAlgorithm),
		defaultAlgorithm: "lz4",
		compressionThreshold: 1024, // 1KB
		stats: CompressionStats{
			AlgorithmUsage: make(map[string]int64),
		},
	}
}

func NewGCManager(threshold float64) *GCManager {
	return &GCManager{
		gcThreshold: threshold,
		stats: GCStatistics{},
	}
}

func (gm *GCManager) RecordGC() {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	gm.gcCount++
	gm.lastGC = time.Now()
	gm.stats.TotalGCs++
}

func (gm *GCManager) AdjustThreshold(delta float64) {
	gm.mu.Lock()
	defer gm.mu.Unlock()

	gm.gcThreshold += delta
	if gm.gcThreshold < 0.1 {
		gm.gcThreshold = 0.1
	} else if gm.gcThreshold > 0.9 {
		gm.gcThreshold = 0.9
	}
}

func NewUsageMonitor(maxHistorySize int) *UsageMonitor {
	return &UsageMonitor{
		usageHistory:   make([]UsageSnapshot, 0, maxHistorySize),
		maxHistorySize: maxHistorySize,
		predictionModel: &UsagePredictionModel{
			historicalData: make([]UsageSnapshot, 0, maxHistorySize),
			modelType:      "linear",
		},
	}
}

func (um *UsageMonitor) AddSnapshot(snapshot UsageSnapshot) {
	um.mu.Lock()
	defer um.mu.Unlock()

	um.usageHistory = append(um.usageHistory, snapshot)
	if len(um.usageHistory) > um.maxHistorySize {
		um.usageHistory = um.usageHistory[1:]
	}

	// Update current and peak usage
	um.currentUsage = snapshot.Usage
	if snapshot.Usage > um.peakUsage {
		um.peakUsage = snapshot.Usage
	}

	// Calculate average usage
	totalUsage := int64(0)
	for _, snap := range um.usageHistory {
		totalUsage += snap.Usage
	}
	if len(um.usageHistory) > 0 {
		um.averageUsage = float64(totalUsage) / float64(len(um.usageHistory))
	}
}

func (um *UsageMonitor) GetPeakUsage() int64 {
	um.mu.RLock()
	defer um.mu.RUnlock()

	return um.peakUsage
}